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Volume 32, Issue 2
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Michiyasu Mori1971 Volume 32 Issue 2 Pages 27-31
Published: September 30, 1971
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSThe hygropetric algal vegetations were studied in the mountains of Kumamoto Prefecture in the summer of 1961 and 1962. The source of spray which makes wet the surface of rocks under consideration may be classifyed into three types. The first is the water derived from cold springs in the valley of Naidaijin-dani, and the second is the water from the outflows of the irrigation canals in the valley of the Shakain-gawa. The remaining type of wet rocks is those sprayed by the flows from the rice-fields in the lowermost part of the latter valley. The algal vegetations on these wet rocks may be classified into the following six associations.
1. The lump of gelatinous colonies of blue-green algae represented by Gloeothece rupestris, Gloeocapsa luteo-fusca, Gloeocapsa montana, accompanied by Chroococcus, Aphanocapsa and Nostoc ..........................................................................................................Type 1.
2. Felt-like growths of Scytonema haffmanni var. crassa...............................Type 1.
3. Tufts of Cladophora glomerata...................................................................Type 2.
4. Felt-like growths of diatoms......................................................................Type 2.
5. The long filaments of Rhizoclonium sp.......................................................Type 3.
6. The slimy membrane of filaments of Phormidium autumnale of Ph, corium............................................................................................................. Type 3. When the source of water changes from underground to surface, the blue-green algal colonies are replaced by the green alga as the dominant, and the latter is succeeded by diatoms, Terpsinoe trigetra and Melosira varians. The last stage of successional change is the occurrence of either the long filaments of Rhizoclonium sp. or the slimy membrane of filaments of blue-green algae on the rocks under the overflows rich in nutritive matters from rice-fields. Under such a condition they are in poor development of sheath or gelatinous matters, while those growing under the spring water show a good development of thick gelatinous matter or firm sheath.View full abstractDownload PDF (863K) -
II. Metamorphosis, growth, seasonal and geographical distributionTetsuo TOMIKAWA1971 Volume 32 Issue 2 Pages 32-39
Published: September 30, 1971
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSThis study deals with Sinodiaptomus volkano Kiefer concerning its metamorphosis growth and its seasonal distribution in Japan.
1. Fourteen stages are observed in metamorphosis, two nauplius, six metanauplius and six copepodid stages. In ecdysis new segments are inserted in frout of the ventral process, i. e. anamorphosis (Fig. 1). The duration between hatching and sex discernible stage varies according to the temperature of water and kind of foods, showing 22-23 days at 17.-18 °C on average. Body length in sex discernible individuals is about 1.3mm.
2. The larva of 0.13mm in body length just after hatching attains 1.08 mm on average after 18 days in summer populations, while that of 0.12 mm long attains 0.70 mm after 22 days in winter populations (Table 1).
3. Growth rate from minimum sex discernible individual to adult is expressed as _??_Y=0.1036X+0.7360 in summmer populations, and _??_Y=0.0719X+0.7693 _??_Y=0.1005X+0.6430 _??_Y=0.0689X+0.5650 in winter populations, where X is days and Y is body length in mm (Fig. 2).
4. This species is eurythermal, occurring in small ponds throughout the year. The winter population is larger in size than those of summer, spring and autumn populations (Fig. 3).
5. The summer populations prefer temperature range from 15 °C to 30 °C, while the winter populations have a preference for a range between 5 °C and 10 °C.
6. It occurs abundantly in ponds on the northern and southern coasts of the Seto Inland Sea covering the prefectures of Fukuoka and Oita, as well as Yamaguchi, Hiroshima, Okayama, Ehime, Tottori and the southern part of Hyogo (Table 2 and 3, Fig. 4).
7. Its common habitats are ponds lying at 50-100 m above sea level. The habitat water is neutral or slightly alkaline and oligotrophic in nutritive conditions.View full abstractDownload PDF (1171K) -
Yoshito WATANASE, Hidetake HAYASHI1971 Volume 32 Issue 2 Pages 40-45
Published: September 30, 1971
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSAs an approach to studies on the decomposition process of suspended matter in lake water, the use of a funnel connected with an Ehlenmyer flask as a collection apparatus (Fig. 1-A and-B) for a short period was examined for measuring the amount of freshly precipitating matter. The results obtained are summarized as follows :
1) The amount of precipitating matter is proportional to the area of funnel, not to the whole volume of apparatus. This may suggest that the trapping effect on suspended matter is not so significant (Fig. 2).
2) The amount of precipitating matter also increases linearly with time spent for collection, unless there is any unusual effect of the temporary movement of lake water or of artificial events (Fig. 3 and 4).
3) The unusual effect of the temporary movement of lake water can be detected by measuring the amount of precipitating matter successively for a few days and plotting its values against the time spent for collection. Insuch a way, the following events were expected : the inflow of water mass heterogeneous in algal concentration (Fig. 4-2), the contamination of bottom mud caused by wind (Fig. 5) or by the effect of artificial events such as anchoring or dredging (Fig. 3), and the stagnation of lake water immediately after being closed by ice (Fig. 6).
4) It is concluded that dynamic status of freshly precipitating matter can be pursued by this method.View full abstractDownload PDF (1010K)
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